Spondylus lucasi Maury, 1920
MAURY, C. J. 1920. Tertiary Mollusca from Porto Rico. Scientific Survey of Porto Rico and the Virgin Islands, 3 (1): 1-77, pls. 1-9. New York Academy of Sciences, New York. [p. 23, pl. 5, fig. 1]
1920 Spondylus lucasi Maury, 1920
C. J. Maury, 1920, plate 5.
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«Shell oval, oblique, small for the genus. The cardinal area is defective and broken, but shows traces of the isodont hinge of Spondylus. The sculpture consists of stronger, low, primary, radiating, rounded threads bearing spines at intervals, and between every two of these primaries are eight to ten or twelve much more delicate radiating lines. The central one of these is slightly stronger than the rest. It does not stand out sharply but the eye can discern that it is a shade thicker. The fine radii between the primaries nearly always alternate in strength, the finest lines of all being visible only with a lens. All of the fine radii are ornamented with minute scales, giving them a beaded appearance, especially on the anterior part of the valve. Approximate altitude of shell 33 mm., estimated breadth 28 mm.
Among the specimens of Spondylus were some fragmentary external molds remarkable for the extreme fineness and delicacy of their sculpture which was imprinted in reverse upon the limestone. A single shell shows the same delicate sculpture in the positive; the
actual substance of the valves being retained. The exquisite sculpture distinguishes this species from the specimens that my party collected in Santo Domingo. Our young shells of Spondylus bostrychites have very much coarser and less numerous radial ribs between the spinose primaries. The large shell, Spondylus gumanomocon has the primaries but little differentiated and frequently the spines are no longer than the coarse, imbricating scales which cover all the ribs alike. Dall has lately described Spondylus filiaris from the Flint River, Georgia, Oligocene. His figure of the young shell (Proc. U. S. Nat. Mus. LI, Pl. LXXXIII, fig. 5) bears at first glance quite a resemblance to the Porto Rican fossil, but the Georgian species has no spinose processes, the radii are quite smooth, and the sculpture not so delicate. There is, however, a very beautiful Spondylus in the Calcaire grossier of Grignon, France. It is Lamarck's S. radula. In form it is quite unlike Spondylus lucasi, but its sculpture is so strikingly like as to be almost exactly parallel. The European Eocene shell is more sharply spinose and more prickly. This shell is named in honor of Dr. Frederic A. Lucas. Localities.— Senor Rabell's Ranch, Rio Guajataca, Station 110; East Shore of Guanica Harbor, Station 370; near Arecibo, Station 509.» CARLOTTA JOAQUINA MAURY, 1920
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«Remarks.— A single left valve from locality TU 1211 (Rio Gurabo; see Saunders, Jung, and Biju-Duval, 1986, text-fig. 5) is here identified as Spondylus lucasi Maury, 1920, originally described from the Guánica Limestone (= Ponce Limestone) and the Quebradillas Limestone of Puerto Rico. The Ponce Limestone, from the south coast, although originally described as Oligocene in age is now considered to be early Miocene; the Quebradillas Limestone, from the north coast, is now considered Pliocene. Although slightly larger than the type of S. lucasi, the Dominican specimen agrees so completely in all details of the ornamentation of that form as figured by Maury (see PI. 2, fig. 3), as to leave little doubt that it represents the second record of its occurrence in the Caribbean fossil fauna.
Comparisons.— The shell of Spondylus lucasi Maury, 1920, has a much more evenly patterned ornament than S. scotti Brown and Pilsbry, 1913, as figured by Woodring (1982, pl. 97, figs. 8-10), from the early Miocene La Boca Formation of Panama, with which he tentatively [p. 601] synonymized S. lucasi. Jung (1965. pl. 55, figs. 2, 3 and 1971, pl. 1, figs. 4, 5) has figured specimens from the early Miocene Cantaure Formation and the early middle Miocene Grand Bay Formation, respectively, that he compares to S. lucasi. Both seem better assigned to S. scotti. Spondylus lucasi and the older S. scotti are similar only to the extent that both have relatively fine radial ribs, in contrast to such species as S. bostrychites Guppy, 1867, in which the ribs are much wider (compare PI. 1, fig. 3b, and PI. 2, fig. 2b). In S. scotti, there are many more major radials (17 in the type specimen) with fewer secondary radials between each pair (four to eight in the type specimen) than in S. lucasi, which has only seven or eight primary ribs, with about seven secondary ribs between each pair of primaries. In the Recent fauna of the Indo-Pacific the species S. anacanthus Mawe, 1823, is perhaps the most nearly similar to this unusual species, which is marked by having a much more regular surface ornament than is typical for most species of Spondylus. Occurrence.— Guraho Formation: Rio Gurabo (TU 1211). Distribution.— Gurabo Formation, Dominican Republic. Ponce Limestone, Early Miocene; Quebradillas Limestone, Pliocene; Puerto Rico.» VOKES, H. E. & E. H. VOKES. 1992. Neogene paleontology in the northern Dominican Republic. 12. The genus Spondylus (Bivalvia:Spondylidae). Bulletins of American Paleontology, 102: 5-13, pls. 1-3. [p. 11]
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Spondylus lucasi Maury; H. E. Vokes & E. H. Vokes, 1992, Neogene paleontology in the northern Dominican Republic. 12. The genus Spondylus, plate 2, figures 2a, 2b, 3.
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